VARIABLE METAPLEURAL GLAND SIZE-ALLOMETRIES IN ACROMYRMEX LEAFCUTTER ANTS (HYMENOPTERA, FORMICIDAE)

Variation in the relative size of the metapleural gland (bulla) was an alyzed for workers of two sympatric but genetically differentiated spe cies from the Acromyrmex octospinosus species complex. For the minor w orkers the increase of bulla width with pronotum width was about isome tric, but the slope of this relationship gradually decreased through t he media to have a slope of around 0.45 for the major workers of both species. Further analysis of relative bulla size in major workers show ed that a significant proportion of the individual variation (35% in s pecies 1 and 22% in species 2) was due to among colony differences. Th e significance of this variation is discussed, with particular referen ce to the antibiotic-producing function of the metapleural gland.